Spark plug



FeB. 17. 1925 1,527,078 H. RABEZZANA, 1

SPARK PLUG Filed Nov. 26, 1919 I j E! 10 v 11 L:

11 i T 8 n 3 3 5 14 4 13 I z a C, C /Q 16 15 awue wfoz HECTOR RABEZZANAFella ll, l fiho si es HEGTQB RABEZZANA, F FLINT, MICHXGAN, AliSIGNOR TOA C SPARK PLUG COM:- Fw @l FLINT, MICHIGAN, A CCDRPOBATION O'JFMIGHIG'AN.

SPARK PLUG.

Application filed November as, isle. Serial ire/smear.

'To 0132 whmn it may concern."

Be it known that l, HECTOR RABEZZANA, a subject of the King of Italy,and a resident of Flint, county of Grenesee, and State of Michigan, haveinvented certain new and useful Improvements in Spark Plugs, of whichthe following is a full, clear, concise, and exact description, such aswill enable others skilled in the art to which the invention relates tomake and use the same,

reference being made therein to the accompanying drawing, thisspecification. Q

My invention relates to spark plugs designed for use in connection withinternal combustion engines for igniting the combustible mixturesupplied to the cylinders thereof; and the principal object of myinvention is to provide a spark plug which will be 2G less liable tobecome short-circuited when in use than has heretofore commonly been thecase in spark plugs.

A. further object of myinvention is to provide a spark plug in whichsuch deposit of soot as occurs when the plug is in use will be localizedat one portion of the surface of the insulator of the plug, while theremaining portion of the insulator will remain in a comparatively cleancondition h and will be free or substantially free from deposited sootwhen the plug is in use.

With the above and other objects in view, my invention consists in theimproved spark plug illustrated in its preferred form in the drawingaccompanying and forming a part of this specification; although it willbe appreciated that the drawing is for illustrative purpose only, andthat my invention includes all such variations and modifications of theparticular embodiment thereof shown in the drawing as come within thescope of the concluding claims Referring now to the drawing: Fig. l is aview partly in section and partly in elevation, and in which my improvedspark plug is illustrated.

Referring now to the drawing, the refer ence numeral 3 designates ametallic shell or casing the lower portion of which is threaded,asindicated at l, and the upper portion of which is provided with aportion 2 designed to be engaged by a wrench in screwing the plug as awhole into and out of a threaded opening providedin the wall which formsa part of of an internal combustion engine cylinder for its reception.

The shell or casing 3 is provided with an internal chamber 5 which iscommonly circular in cross-section, and the inner'end of the casing andof the plug is provided with an opening or passage 6 leading into thechamber 5; and which; opening is of less diameter than the diameter ofthe chamber. 5, so that the inner end of said chamber ispartially closedby an inwardly extending ledge 7 at the lower end of the casing 3.

The inner end of the insulator above referred to is reduced in diameteras is shown at 8, in order to thereby provide a dead gas chamber orpocket 9 surrounding the portion of the insulator which projects intothe chamber 5, as is usual in spark plugs of the type to which myinvention relates. The insulator is held. in place within the shell 3 inthe embodiment of my invention illustrated by bending over an annularledge or collar at the upper end of the casing, as shown at 10; suitablecushions 11 being provided between the upper and lower faces of theenlarged central portion 12 of the insulator and the adjacent portion ofthe metallic shell in order to thereby avoid the breaking of theinsulator in turning down the flange 16 to secure the insulator inplace. lt will be appreciated, however, that the invention to which thisapplication. relates is in no way involved in or is concerned with theparticular manner in which the insulator is held in place within themetallic. casing, and that the same may in fact be held in place in anyof the ways at present in use for holding the insulating body of'a sparkplug in place in the exterior metallic shell or casing thereof. I

The inwardly extending portion 8 of the insulator is preferably madeconical in form, as shown, and the inner end or head 13 of the insulatoris larger than the onening 6 at the inner end of the shell; and theperipheral surface of said enlarged inner end is preferably curved inform and substantially spherical iii-shape, or rather in the shape of asegment of a sphere; from which it follows that the peripheral surfaceof the said enlarged inner end inclines away from the opening 6 adjacentwhich it lies when the insulator is secured in place within the casing.This enlargement of the till central electrode extending through apassage formed in the insulator, and which electrode is insulated fromthe shell or casing by said insulator; while the reference numeral 16designates an external or outer electrode carried by the inner end ofthe easing and the extremity of which lies adjacent the inner end of theelectrode 15, sothat the sparks'will pass between the two electrodeswhen the plug is in. use. It will be appreciated, however, that theconstruction of the, plug as regards the outer electrode may be suchthat the sparks pass from the inner electrode directly to the shell orcasing, should such a :form be deemed desirab e, as my invention is notconcerned with the articular construction and arrangement of t e outerelectrode of the plug.

In view of the premises it will be appreciated that when the plug. is inuse there will be a surging of gas through the opening 6 and intoand outfrom the dead gas pocket 9, due to the alternate high and low pressureconditions present within the cylinder.

The greater part of the flow of gas will be in a direction substantiallyalong the axis of the plug as a whole, as indicated by the arrow at, andsuch oil, carbon, or other entrained matter as may be present in the gaswill be projected directly against the end of the head, where it will bedeposited throughout an area corresponding approximately with the areaof the passage 6; as the impact of the carbon particles carried by thegas which flows through the opening toward the insulator results in suchparticles being arrested by the surface of the head 13 with which theycontact, where they remain as a deposit upon said surface.

The deposit of soot upon the end of the insulator will be localized uponthe exposed end of the enlarged head 13-and will ob viously have littleor no effect in short-circuiting the pin while the portion of theinsulator beyon or above the area at which the principal part if not allof the soot is deposited will remain comparatively tree from a depositof soot, oil, or other objectionable material.

Suchgas as may flow through the opening 6 in an inclined direction,-asindicated by the arrow 5, will be deflected by the side wall of the oening against the end of the insulator, wit a resulting deposit of suchcarbon particles as the gas in question may carry upon the end of theinsulator the same 'us in the case of an axial flow heretotorcconsidered; while such gas as may be deflected by the head out theinsulator and caused to nae-acre flow along the inclined path indicatedby the arrow 0 will be deflected by the interior wall' of the chamber 5against the side of the insulator above the'ledge 14. The quantity ofgas, however, not coming into direct contact with the exposed lowersurface of the head 13 will be comparatively small, and such carbon asmay be swept into the dead gas pocket 9 and deflected against theinsulator will be deposited thereupon above the ledge 14; as theconstruction and arrangement of the parts is such that the impact ofsuch gas as may flow or be deflected along the paths indicated generallyby the arrows c with the peripheral surface of the insulator occurs wellabove the ledge in question.

It therefore follows that by far the greater'amount of soot orequivalent material deposited upon the insulator will be localized uponthe under surface of the enlarged head thereof, and that suchcomparatively small portion as may in fact be carried ast the enlargedend of the insulator and into the dead gas space 9 by the in flow of gasthereinto will be deposited upon the insulator well above the ledge 14provided by the enlarged head 13; the construction of plug hereindisclosed thus maintaining the peripheral surface of the insulator abovethe ledge 14 comparatively tree from a deposit of soot, and entirelypreventing the deposit of soot throu hout a band or zone of someconsiderable wldth immediately above the said ledge.

Having thus described and explained my invention, I claimand desire tosecure by Letters Patent:

1. In a spark plug, a metallic shell or casing having an internalchamber, and an opening of less diameter than said chamber formed in theend of said casing and leading into said chamber; an insulator having abody portion the periphery of which is smooth throughout its entireextent, and

which body portion extends into and is'of less diameter than saidchamber, so as to provide a burned gas pocket surrounding saidinsulator, the end of said insulator being enlarged and lying adjacentthe opening aforesaid in said casing, and the peripheral surface of saidenlarged end inclining away from said opening; and an electrode carriedby said insulator.

2. In a spark plug, a metallic shell or casing having an internalchamber, and an opening of less diameter than said chamber formed in theend of said casing and leading into said chamber; an insulator having abody portion smooth throughout its entlrc extent'extepding into saidchamber, and which body portion is or less diameter than the diameter ofsaid chamber, so as to provide a burned gas pocket surrounding saidinsulator, the extremity of said insulator lying adjacent the openingaforesaid and 1:50

1,627,078 v v e bein enlarged relative to the main body portion thereof,and of smooth convex form throughout its entire extent, to therebyprovide a ledge adjacent to the end of said insulator; and an electrodecarried by said insulator.

3, In a spark plug, a metallic shell or casing having an internalchamber, and an opening of less diameter than said chamber formed in theend of said casing and leading into said chamber; an insulator having amain body portion conical in form and smooth throughout its entireperipheral surface extending into, and which is of less di ameter thansaid chamber, so as to provide a burned gas pocket surroundingsaidinsulator; the end'of said insulator lying adjacent the openingaforesaid, and being enlarged relative to said opening and the main bodyportion of said insulator, to thereby provide a ledge adjacent to theinner end' thereof, the peripheral surface of said enlarged end'beingconvex andinclined away from said opening, and smooth throughoutitsentire peripheral surface; and an electrode carried by said insulator.

In testimony whereof I ainx my signature. HECTOR RABEZZANA.

